Mechanism for the control of electric steam generators



July 31, 1928. 1,678,995

W, D. MAXIM ET AL.

. MECHANISM FOR THE CONTROL OF ELECTRIC STEAM GENERATORS Filed D650. 14, 1926 I 11v VENYLORIJ WK Z/WW B Y J,

Fatented July 31, 1928.

4 UNITED 1 STATES l PATENT OF FlECEiE-Jl WILLIAM D. MAXIM AND EVERETT IIIAIIANNKH, OF NEW YORK, N. ,Y., ASSIGNOBS T INTERNATIONAL PAPER COMPANY, A OOREORATION OF NEW YORK.

MECHANISM FOR THE CONTROL OF ELECTRICSTEAM GENERATORS-.1

Application filed December 14, 1926.2 SerialNo. $4,840.

This invention relates to the control of electric steam generators of the type in which a plurality of boilers or tanks are employed and the water therein heated by an electrode in each-boiler supplied with the heating cur rent from a common bus line, the amount of current'acting onnthe water in each tank depending; of course on the level of the water therein and the degree of submersion The invention is particuof the electrode. larly concerned: with steam generators of this nature :known in'the trade as theKaelin three tankztype, and the accompanying drawings show theinvention applied to such type although it is applicable, as will be apparent to those skilled in the art, to steam generators of this typeof other specific forms, and employing a greater or less num i the steam generators being interrupted by the protective relays which it is customary to install in the power line, such interruptionresulting in loss of production.

The present invention aims to prevent the occurrence of such objectionable conditions, and it consists of electrically actuated means, operatingautomatically to control the supply of feed water to the respective tanks, according to variations, within certain limits, which mayoccur in the amount of current-in ainperes acting in therespective tanks, the said means acting to shut off the ieedwater to that-tank or tanks in which the current supply increases by a given percentage beyond that of the. other tanks and acting to again open the feed Water supply when the current supply has been so i'ar reduced as to balance that of the other tanks; whereby the current supply to all ofthe tanks will be automatically maintained at the sameampere strength and the balance of the tanks preserved. I'n the specification to follow, the form and construction of the parts by which the above described operations are brought about. will be described in detail, and thenovel features thereof pointed out in the appended claims} In the accompanying drawings:

The figure is a diagrammatic view Show ing a battery of three electric steam. generators with my invention applied thereto/ 0 Referring to the drawings: V

The steam generating boilers or tanks to be controlled are designated respectively by reference numerals 1, 2 and 3, there being 5 in the present instance as illustrative :otthe a invention by way of example three of these tanks, each equipped with an electrode l connected electrically respectivelyvby leads 5, (5 and? to the "three phases of-ia supplybus line 8, electricalconnectionsbeing provided: between the tanks, and the latter, grounded as usual so that the current will flow through the bodiesof water between the electrodes andsides ofthe tankshand -will lieatthe same, all in the manner well-p:

known'inthisart, it beingunderstoodol course that the amountioi current in am- 1 peres acting. on the'water in a tank will;de pend upon the Water level therein, and con sequent-1y. upon the degree. of submersionv of the electrode. o V a a The tanks are supplied with water from a 3 feed-water main 12-i rom whieh'branch'pipes 13, 14am '15 lead to the bottoms'of the re- .35

'spective tanks. 1 Thebranch pipeshare equippedrespectively with cut'ofl' valves 16,

17 a and 18 operatively connected with oper-i ati'ng cores 19, 20 and 21 actuated by sole-wnoid coils22, 23 and 24, which coils are connected in electric circuits .tobe described, more'in detail later on, thesaid solenoids and cores constituting: :electro-magnetio: valve operatingmeans.

Connected in series with'the branch conductors 5 6 and? of the incoming bus-line, are current transformers 25, 26 and 2710f the proper ratio ..to deliver" a 5 ampere "secondarycurrent;under the maximum load on the tank circuit or bus line, to secondary cir: cuits 28, 29 and 30, which-secondary circuits are connected toa differential relay"3l.:. Thisrelay which is of a well known commercial type is composed of threeelements 32, 38 and 84:, each element comprising an:;1 05 operating coil 35 and a retarding coil-36- mounted respectively on horseshoe magnets 37 and 38, and a copper disk 39 carried by an operating shaft 39*,

operates a switch plate 39", which at the end of the rotation of the shaft, makes contact with a pair of silver contacts, there being ofcourse one pair of contacts for each element, a pair 4:0 for element 32, a pair ll for element 33, and a pair 4:2 for element 34. These pairs of contacts are included respectively in electric circuits 43, a l and- 45, which circuits are connected in parallel respectively with operating coils 46, dTa-nd d8 of three single-pole contactors or switches 49, 50 and 51 of Well known form, including each afixed contact point d9 and a movable contact arm 49".

The circuits 43, 4A and 45 are supplied with electric current, in the present instance a direct current, from a power line by conductors 53, 54 and 55 branching from one side 52 of the power line and connected respectively to one of the ends of the operating coils of thethree single-pole contactors, the said conductors being furnished respectively with suitable resistances 53. 54% and 55 to prevent overload of the circuits when contacts in controlling the height of the water level, the said switches being operated in the present instance by expansion tubes 66, 67 and 68 communicating at opposite ends respectively with the steam space and water in the several tanks and operating by expansion and contraction, as steam or water enters the tubes, to move the switches and close or open the circuits through the'contact points. The arrangement of the parts in the present instance is such that under normal conditions of operation with the water level atthe proper height, the switches will be held in engagement with the pairs of contact points, thereby closing the circuits, but in the event of the Water rising to an undue level where it might flood the steam pipe, the switches will be moved and disengaging the pairs of contacts thecircuits will'be opened, it being understood of course that there is one of these water level controlling switches for each tank, and that they are operative independently of each other. As aresult of this arrangement and construe tion of the parts, it will be understood that under normal operatingconditions, the three operating coils of the single-pole contactors will be energized by the current of the power and rotating between the pole pieces of the magnets. Each shattcircuit traversing said coils through the normally closed circuits controlled by the highwater level switch, under which conditions the circuits d3, and d5 controlled by the dii'lferential-relay will be open.

The solenoid coils 2:2, :33 and 242 which operate the teed-we t r valres, are connected at one end resi icctii iy by means of conductors 69, 7t) and il to the side 52 of the power line, by a common conductor 72, the said coils being connected at their opposite ends respectivelyby conduc "is 73-, 7d and 75 to the fixed contact poll 429 of the three singlepole contacto 50 and 51, the movable contact arms oil which contactors are connected respectively by conductors 76, 77 and 7 8 to the side oi? said power line.

As a result 01" the connection of the valveoperatin'g solenoid coils and the single-pole contactors in the power-line as described, it will be "tuiderstood that wnen the pole contactors are in closed position, the solenoid coils will be energized, and due to the connection of the armature cores 19, 20 and 21 with the respective feed water elves, which connections in this form of the iuvention are such that when the cores are actuated by the energized solenoid coils, the valves will be held in opened position, said valves will be opened when the solenoid coils are energized; and when said coils are deenergized, the valves will be closed by suit able springs prov led for that purpose,

The operation of the parts so far described is as follows: i

Under ordinary normal operating conditions, with the current supplied to the threev tanks in loalance or at the same valve, the three pairs of relay contacts L0, all and 42 will be in open position, and the operating coil-s 4.6, 47 and of the three single-pole contactors d9, 50 and 51 will be energized by the current oi the power-circuit traversing said coils as hereinbettore described, which will hold the movable contact arms of these pole contactors in contact with the fixed contact points of the same. The electric circuits through the valve operating solenoid coils being thus closed, the cores connected with the valves will beactuated and the valves held in open position, thereby admitting feed water to the several tanks. The water will continue to flow to the tanks as long as the at rementioned balanced condition exists, but in the event that the current to one of the tanks exceeds that of either of the other two, thereby destroying the balance previously existing, the torque of that operating coil of the relay connected. in the secondary circuit of the tank in which the e}:- cessive current occurs, will. overcome the torque oi the corresponding retarding coil of the relay and will cause the associated disk to rotate in a direction to close the contacts of that particular element 01" the relay.

By fthis' means :the' current tromthe power line, Will baby-passed around that coil of be opened, thereby deenergizing the solenoid c011, and pelnlltl lng lLlIG fQQCl" water valve to clos'e,-so that the supply of water-to the =tank-receiving the excess ofc'ur'ent'will be shutoff. In by-passing the power "current 1' low cost. It 1s operated directly by the i' ac- I torwhich it is desired to control, viz, elec V aroun'd the operating coil of the singlehpole contactor "as described, the current'niay'be traced as follows, assuming for examplethat the 'eXcessof current-occurs in tank 8. The

circuit being closed by the differential relay actuated by the excess asecondary current of the tank 3, the current 'Jfroml the-side 52 of the power 1 circuit i will, .due" to the; resistance offeredi-by theilcoil' 46, passtidirectly to the closed circuit=l3 iby ioonductor 53,-and "will leave Ysaidcircuit "by: conductor 56 .':without.

traversing:the t'coil 4.6,;and will pass thence to oontact point-r59; switch 66, 'contactopoint 62 iandrby; conductor 65 to the other side 52 of theilpower circuit, the power current being thus 'shuntedior by gp'assed around thecoil and deenergizinm'thez same; .:The: t'eed 'water to theitank being shut ofi'" bythe deenergizing of the coil :46 as described,therwatcr-rema1n ingein thetankavill boilsdowniuntil: apoint is reached where' the :current-zfiow through the operating coils of the pole cont-actors normally deenergized, and the pole con the Twvatei: will be the same, L01 perhaps slight- 1y Eless,-- than. that of eaehot the other two tanks, and whenwthis point is reached, the: torque-on the previously actuated operatingcoil? of the relay being relieved, the associatedadisk I Will a return to (its former lp ositio'n,

the previously closed -:relay :contacts will be v OPGDGClgwlihfl pole contactor closed .due to the reenergizing. of its'operating coil, whereby thewvalve-operating solenoid coil will again beenergized, and the feed. waterwvalve again iopened to ladmit water to "the boiler;

In t practice the differential relay: Willi be so adjusted or set'that it will not operate to close-the circuits controlled by it, unless. the

current in one tankexceeds-that-ot either of a the other two'byb or'6%,-sinee=it hasr'been found-in practice that a smaller percentage;

of unbalancell will I1Ot=Tbe seriously: obj'ecftionable. It. willx-be-eunderst ood however that therparts may beset to operate undercondi-tionsiinvolving greater or-less per centage i of r excess without departing. from the spirit of theri-nventiona H From the foregoing description and detailed construction"and-operation of the parts it will be understood that as along-Mas out iofl,ithereby preventing further increase of current in that tank; and when by reason of the lowering of the level of the water by the. continued generation of steam without supplying more water, the current reaches its former strength 1n balance? withthe current in the other tanks, the feed water will i be; instantly and automatically admitted 1 again. 7

The improved system of control possesses theadvantages o'r simplicity, reliability, and

trio ourrent, and it not affected by boiler scale,: differences in density or height olthe Water, variations in the length of the elec trodes,*or temperature, or pressure.

lVhile in the arrangement 01'. parts shown andfidesoribed, the feed water valves are described as being held normally open by the solenold code when energized, under whlehbe held in open position when controlling circuits will benormally open,

tactors normally open. LUnder such a reversedarrangement of the parts, any excess ofcurrent in one tank, will, as, before, act;

automatically to shutoll the ieed water to that tank;

WVhile in the foregoingdescription andaccompanying drawings we have set; forththe invention in the particular detailedi orin' which we prefer to adopt, it will beunder-' stood that these details may be variously" changed and modified by the skilled-mm ohanic without departing from the spirit the invention; and further it will be' linden stood that the invention is not hunted to any particular form or construction of the parts,

except in so far as such limitations are sneezfied in the claims. t 7

Having thus described our invention, What We claim is: o

1. In combination with a plurality of electric steam enerating tanks, meanslor su 3- b plylng the same with electric current to heatthe-water therein, a feed water supply for each tank; an electrically operated means for each feed water supply, said several electrically operated means being supplied with currentfrom a common source, and an eloctrically operated'controlling device for each of'said electrically operated means supplied with current from said common source, and being adapted, by an excess of currentin source, and an electrically operated con-v trolling device for each of. said valve operating means supplied with current from said common source, and being adapted by an excess of current in one tank over that in another tank, to close the feed water valve of that tank in which the excess of current oc- CUTS.

3. In combination with a plurality of electric steam generating tanks, means for supplying the same with electric current to heat the water therein, a feed water supply for each tank, a valve for each feed water sup ply, an electrically operated means for each valve supplied with current from a common source, and an electrically operated controlling device for each of said valve operating means supplied with current from said common source, and being adapted by an excess of current in one tankover that in another tank, to close the feed water valve of that tank in which the excess of current occurs,

said controlling device operating to open the valve when the current value again equals that of the other tank.

4. In combination with a plurality of electric steam generating tanks, means for sup.- plying the same with electric current to, heat the water therein, a feed water supply for each tank,'a valvefor eachteed water supply, an electrically operated means for each valve supplied with current from a common a source, an electric relay actuated by tne heating-current, and an electrically operated controlling device for each of said valve operating means, said controlling devices being supplied with electric current from said common source and being controlled in their action by said relay.

5. In combination with a plurality of electric steam generating tanks, means for supplying the same with electric current to heat the water therein, means for supplying feed water-to the tanks, valves for controlling the flow of the water, electro-magnetic means for operating said valves, electric circuits includ ing said means and supplied with current from a power line, electric switches in said circuits controlling the flow ot the current thereto from the power line, an electric relay adapted to be operated by the heating current, and normally open circuits including said switches and adapted to be closed by the relay when actuated by the heating current. r

6. In combination with a plurality of electric steam generating tanks, a bus line for supplying the same with electric current to heat the water therein, circuits supplied with secondary current from the bus line circuit, a differential relay connected to said secondary circuits and operated thereby, means for supplying the tanks with "feed water, valves for controlling the flow of the water,,electro-magnetic means for operating the valves, electric circuits including, said means and, supplied with current from a power line, and means actuated by said relay for controlling the supply of the current from the power line to the circuits of the valve operating means.

' 7. In combination with a plurality of electric steam generating tanks, means for supplying the same with electric current to heat the water therein, means for supplying teed water to the tanks, valves for controlling the flow of the water, electro-magnetrc means for operating'the valves, electric circuits-ins cluding said means and supplied with current from a power line, electric switches in said circuits for controlling the flow of currentthereto from the power line, operating coils for said switches, normally closed circuits connected with the power line and including saidoperati-ng coils, normally open circuits including said operating coils. and adapted when closed to shunt the power current around said coils, and an electric relay adapted to be actuated when the current in one tank exceeds that in another and operating when so'actuated to close the normally open circuit connected with the coil of that switch whiehcontrols the circuit operating the valve of the tank in which the excess of current occurs; whereby under normal conditions of operation the several coils of the switches will be energized and the feed wa ter valves will be maintained in open posiion, but when an excess of current inone tank occurs, the power circuit being shunted aroun'd the operating coil of the switch controlling that tank, the said coil will be deenergized and the feed water valve closed.

8. In combination with a plurality of electric steam generating tanks, means for supplying the same with electric current to heat the water therein, means for supplying feed water to the tanks, valves for controlling the flow of the water, electro-magnetic means for operating the valves, electric circuits including said means and supplied with current from a power line, electric switches in said circuits for controlling the flow of the current thereto from the power line, operating coils for said switches, normally closed circuits connected with the power line and including said operating coils, means in said a normally closed circuits adapted to be operated to open the circuits when the water in the tanks rises to a predetermined level,

normally open circuits including said operating coils and adapted when closed to shunt the power current around said coils, and an electric relay adapted'to be actuated when the current in one tank exceeds that in another and operating when so actuated to close the normally open circuit connected with the coil of that switch which controls the circuit operating the valve of the tank in which the excess of current occurs.

9. In combination with a plurality of steam generating tanks, means for supplying the same with electric current to heat the water therein, means for supplying feed water to the tanks, valves for controlling the flow of the water, electro-magnetic means for operating the valves, electric circuits including said means and supplied with current from a power line, electric switches in said circuits for controlling the flow of the current from the power line, operating coils for said switches, normally closed circuits connected with the power line and including said operating coils, normally open circuits also including said operating coils and adapted when closed to shunt the power current around the coils, and means adapted to be actuated when the current in one tank exceeds that in another and operating when so actuated, to close the normally opencircuit connected with the coil of that switch which controls the circuit operating the valve of the tank in which the excess of current occurs.

10. In combination with a plurality of electric steam generating tanks, means for supplying the same with electric current to heat the water therein, valves for controlling the flow of the water, electro-magnetic means for operating the valves, electric circuits including said means and supplied with'current from a power line, electric switches in said circuits for controlling the flow of the current thereto from the power line, operating coils for said switches, circuits connected with the power line and including said 0-perating coils, other circuits including said operating coils and adapted to shunt the power circuit around said coils, and an electric relay adapted to be actuated when the current in one tank exceeds that in another,

and operating when so actuated to shunt the power circuit around the coil of that switch which controls the circuit operating the valve of the tank in which the excess of current occurs. 7

In testimony whereof, we have aflixed our signatures hereto.

WILLIAM D. MAXIM. EVERETT A. MAHANNAH. 

